Inv. Banking much more profitable so easy choice.

On a bot deal broker is on the hook for the issue but they will not enter into that deal until they have orders from instit. for the majority of same.

Sometimes you'll notice a deal on a "best efforts" basis. Not enough instit. interest so retail gets an opportunity & broker is not on the hook for any remaining balance.

"Green shoe" means brokers order book not quite high enough to go on the hook for amount wanted by company but if interest develops entire amount will be done with no residual balance held by broker.